The loss of control defence is a partial defence to the crime of murder in the jurisdiction of England and Wales. It was created by section 54 of the Coroners and Justice Act 2009.^[1] The definition of "loss of control" in the Act is defined in a way that requires multiple requirements to be met, and with a number of listed exceptions that can render the defence inapplicable.

The loss of control defence does not exonerate the person who loses control; instead it downgrades the charge for that person from murder to manslaughter, and does not change the nature of the offence for other perpetrators who may have been involved.^[1]

The partial defence of loss of control was introduced to replace the partial defence of provocation, which was abolished by the same legislation.^[2][3]